Assessment of pelvic floor muscle contraction with palpation, perineometry and transperineal ultrasound: a cross-sectional study

Objective To study the correlation between palpation, perineometry and transperineal ultrasound for assessment of pelvic floor muscle contraction and to define a contraction scale for ultrasound measurements. Methods This was a cross-sectional study of 608 women examined with palpation of pelvic floor muscle contraction, using the Modified Oxford Scale, and measurement of the vaginal squeeze pressure with a vaginal balloon connected to a fiber-optic microtip transducer (perineometry). Transperineal ultrasound was used for measurements of levator hiatal area and anteroposterior (AP) diameter in the plane of minimal hiatal dimensions, at rest and on contraction. The pelvic floor muscle contraction was expressed as the percentage difference between values at rest and on contraction. Spearman's rank was used to test for correlation between the different methods of assessment. Results Significant correlations were found between all assessment methods (P<0.001). Palpation correlated with perineometry (r(s)=0.74) and with proportional change in hiatal area (r(s)=0.67) and AP diameter (r(s)=0.69) on ultrasound. Perineometry correlated with proportional change in hiatal area (r(s)=0.60) and AP diameter (r(s)=0.66) on ultrasound. We defined a contraction scale based on the proportional change in AP diameter. In this population, a change in AP diameter of <7% corresponded to absence of contractions, 7-18% corresponded to weak contractions, 18-35% corresponded to normal contractions and >35% corresponded to strong contractions. Conclusions We found moderate to strong correlation between ultrasound measurements, palpation and perineometry for assessing pelvic floor muscle contraction. The proportional change in levator hiatal AP diameter was the ultrasound measurement with strongest correlation to palpation and perineometry and formed the basis for the contraction scale for ultrasound measurements. Copyright (C) 2015 ISUOG. Published by John Wiley & Sons Ltd.